The field of the invention is that of the networking of data processing systems or computers and, more particularly, that of the switchable connection of Local Area Networks ("LANs") such as those supported by the Ethernet protocol and Wide Area Networks ("WANs") such as those supported by the Asynchronous Transfer Mode ("ATM") protocol.
One of the major problems in the field of connecting networks is that the variety of different network protocols used to communicate between different data processing systems on particular networks makes communication between such networks difficult. Another major problem is that most network protocols require considerable configuration of parameters when adding computer systems or nodes, typically accomplished by manual input of device addresses by network professionals who nonetheless make mistakes. This problem may be exacerbated when connecting across network boundaries.
Current connection of networks, including the mechanisms used to connect the Internet, is accomplished using devices known as "bridges" and "routers." Roughly speaking, bridges connect different networks at the "data link" layer or Layer 2 (also known as the MAC layer) of the OSI Network model, see Schwartz, Mischa, Telecommunication Networks at 75-99 (Addison-Wesley 1987), and routers connect different networks at the "network" layer or Layer 3 of the OSI model, A. packet of data is preceded by headers corresponding to layers of communication, with the first in time header corresponding to the lowest Layer 1, the physical link, and proceeding up to Layer 7, the application layer (other models have fewer layers). The "application layer" here refers to functions at Layers 5-7 of the OSI model. When packets of information are received at a bridge, the bridge processor forwards the packet on a data link according to the information in the data link header (following the physical link header). When packets of information are received at a router, the packet is routed according to the information in the network header. These headers, however, do not contain information about the quality of service required by the application to which the data packet pertains; thus, each packet is forwarded according to the data link or network protocol which may or may not include a priority flag, typically for network management operations.
The types of applications requiring data transmission on current networks call for a wide range of service. Thus, in communications with a file server, requests uploaded from a client for downloading of data require relatively little bandwidth, while downloading of massive amounts of data requires great bandwidth to be accomplished in a reasonable time. Streaming of audio-visual ("multimedia") information requires guaranteed bandwidth at regular intervals to avoid perceivable interruptions or "jitter". E-mail, file server requests, HTTP, word processing each have their own application protocols with associated header information that can be associated with their communication needs, including bandwidth.
Network switching schemes that consider information above the network layer, so-called "Layer 4 switches," are just coming on the market and appear typically to involve software implementations that are slow and only consider a portion of the Layer 4 or transport layer header (the "TCP" part of TCP/IP or transport control protocol/internetwork protocol).